After Nick Holonyak invented the practical visible LED in 1962, the first commercial products were limited in brightness and only to applications such as red indicator lights and seven segment displays. In the 1970’s, yellow and green LEDs joined the family and were designed into products such as calculators, but still were not able to produce ambient light.

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Figure 1. Zhaga’s specification formulation process.
In the late 80’s to early 90’s, LEDs took large leaps forward, with the first blue LEDs, the advent of high brightness capability, and the use of phosphor coating to create white light. Technological improvements enabled even brighter LEDs, which enabled the move into progressively higher lumen applications: flashlights, signage, brake lights, traffic lights, and finally ambient lighting applications.

altToday, LED lighting products offering more than100 lumens per Watt (LPW) are not uncommon and provide very efficient energy use compared to traditional light sources. These LED products are showing up in all types of form factors with some fitting into traditional sockets and some using custom interfaces. The challenge is to optimize LED Lighting performance in a product that is convenient for the building occupant.

FAQ #1: If LEDs last forever, why do we even care about end-user replacement?

The answer is that most of them last a very long time, but not all of them, so they must be replaceable. Many early LED luminaires were designed with the LEDs permanently affixed to the luminaire to maximize light output and thermal efficiency. This was considered acceptable because LEDs can last 50,000 hours and longer. LEDs are indeed capable of long service lives, but like all electronic products, they still have mortality rates and are susceptible to damage from broom handles, forklifts, and water leaks. They need to be replaceable by the building occupant if we want efficient LED technology to succeed in broad applications.

Also, when more efficient light engines become available, does it make sense to swap “lamps” or replace entire luminaires? The DoE’s Designer Roundtable on the subject cited replacement parts and lack of modularity as major drawbacks to LED adoption. NEMA recognized this in its 2009 white paper, LSD 44 “Solid State Lighting—The Need for a New Generation of Sockets & Interconnects”:

“Currently, in many LED fixtures, the LEDs are considered "permanent" and cannot readily be replaced in the field by end users or field service personnel. Some LED fixtures treat the LEDs as parts of sub-modules that could be replaced, but are not necessarily constructed in a manner for a “simple” swap without major disassembly of the fixture…. Growing experience with LEDs shows that failures do occur…”